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The biological importance of organophosphorus compounds containing a carbon-phosphorus bond.

Organophosphorus anticholinesterase compounds may be derivatives of phosphoric acid or of a phosphonic acid. The phosphonic acid derivatives are usually more reactive and more toxic than the phosphoric acid derivatives. Examples are given to show that differences in the chemical and biological reactivity of phosphates and phosphonates reflect many different aspects of their chemical structure. Some recently discovered naturally-occurring phosphonates are described, together with some synthetic phosphonate analogues of naturally-occurring phosphates. The utility of these synthetic phosphonates as tools for probing enzymic reaction sequences is discussed.

Animals↗
PubMed1975

Organophosphorus esters causing delayed neurotoxic effects: mechanism of action and structure activity studies.

Evidence is reviewed that the initial biochemical event leading to delayed neurotoxicity is phosphorylation of the active site of a specific enzyme called Neurotoxic Esterase. This is followed by a bondcleavage (? hydrolytic) leading to formation of a mono-substituted phosphoric acid residue on the protein. The mechanism by which some phosphinates protect hens against neurotoxic compounds is explained. Screening Assay. Assay of effects of compounds on Neurotoxic Esterase activity of hen brain in vitro and in vivo provides a quick biochemical screen to supplement the 3-week clinical test. This test provides an estimate of safety margin for compounds which give negative results in the clinical test and are currently used as pesticides, plasticisers, etc. Simplified assay procedures are being developed. Structure/Activity Studies. Data is now available for the biochemical and neurotoxic activity of many compounds. This provides a basis for structure/activity predictions; neurotoxicity data published since 1930 has been assessed in this light.

Animals↗
PubMed1975

Photoreactions of phosphorothioate and cysteamine-S-phosphate. Photosubstitution and photophosphoryl transfer.

The photoreactions of phosphorothioate and cysteamine-S-phosphate were investigated. On irradiation of phosphorothioate a marked change in absorption spectrum was observed. The product migrated in high voltage electrophoresis, with different mobility from that of phosphorothioate and its dimer, or inorganic orthophosphate. It contained phosphate and sulfur in a ratio of 2: 1, without reducing properties. Therefore it was suggested that the product is either pyrothiophosphate, or a cyclic compound, with similar composition. On irradiation of phosphorothioate in the presence of potential phosphoryl group acceptor, such as glucose or galactose, 25-40% of the phosphoryl group was transferred. The formation of glucose 6-phosphate, or galactose 6-phosphate was observed. The photolysis of cysteamine-S-phosphate gave cysteamine, inorganic orthophospate and taurine. Under the same conditions of irradiation, inorganic orthophosphate or aminoethanol-O-phosphate were found to be stable.

Cysteamine↗
PubMed1977

Effect of three nematicides on the growth of some phytopathogenic bacteria and fungi.

The effect of three nematicides, aldicarb, fensulfothion, and phenamiphos at four concentrations (1, 5, 25, and 125 ppm) was tested on the growth of five bacteria, Agrobacterium tumefaciens, Corynebacterium fascians, Erwinia carotovora, Pseudomonas solanacearum, and Streptomyces scabies and four fungi, Fusarium oxysporum f. sp. vasinfectum, Fusarium solani, Rhizoctonia solani, and Sclerotium bataticola. Of the bacteria, P. solanacearum was most affected by the chemicals at all concentrations, while E. carotovora was least affected. Fensulfothion was generally the most effective nematicide on the bacteria tested, while phenamiphos was the least effective. Similarly, the effect of the chemicals on the fungi tested varied greatly. F. solani and R. solani were generally most affected, followed by F. oxysporum, while S. bataticola was least affected. Of the chemicals tested, phenamiphos was generally the most effective, followed by fensulfothion, while aldicarb was the least effective.

Aldicarb↗
PubMed1979

Specific heavy metal labeling of the 3-'terminus of phosphorothioate modified yeast tRNAPhe.

Yeast tRNAPhe containing a phosphorothioate modified -CS-CS-A terminus binds two moles of chloroterpyridineplatinum(II). This result was determined by titrating the tRNA with [3H](terpy)PtCl] Cl, removing excess platinum by cation exchange chromatography, and determining the amount of bound platinum by radiocounting techniques. It has thus been established that adjacent phosphorothioate modified nucleotides can be labeled with an electron dense stain, a necessary requirement for electronmicroscopic sequencing of polynucleotides to become practical.

Kinetics↗
PubMed1976

Synthesis of aziridinylallylaminophosphine oxides and sulfides as potential adjuvant cancer chemotherapeutic agents.

Bis (1-aziridinyl)(hexahydro-1H-azepin-1-yl)phosphine sulfide, an active anticancer agent with low hematopoietic toxicity in animals and man, was recommended several years ago for breast cancer adjuvant chemotherapy as an alternate drug to thiotepa. This hope had led to the syntheses of aziridinylallylaminophosphine oxides or sulfides (compounds I-XVII) in our laboratories. The resurgent interest in this area of cancer chemotherapy encouraged us to report our synthetic work as well as their evaluation as both anticancer agents and insect chemosterilants. Based on observed antitumor activity in animals, low chemosterilant activity in female species (insects and rats), and histochemical observation of tissue toxicity in rat testes but not in ovaries, these new agents are of potential interest to the breast cancer adjuvant chemotherapy program.

Animals↗
PubMed1977

Selection of an in vitro carcinogenicity test for derivatives of the carcinogen hexamethylphosphoramide.

The demonstration that hexamethylphosphoramide (HMPA) possesses potent carcinogenic properties has raised doubts about the safety of exposure to other phosphoric amides. In order to define a suitable short-term test with which to evaluate such analogues, the response of the Salmonella typhimurium mutation assay of Ames and cell transformation assay of Styles to HMPA and 3 selected analogues has been studied. These analogues were the related leukaemogen phosphoramide, the putative non-carcinogen, phosphoric trianilide and N.N'N''-trimethylphosphorothioic triamide, a compound of unknown and hitherto unpredictable properties. While both tests found the trianilide negative, the Ames test failed to detect phosphoramide as positive and gave an erratic and predominantly negative response to HMPA. In contrast, the transformation assay found both phosphoramide and HMPA positive. This test response profile indicates that the transformation assay is the preferred test with which to evaluate analogues of HMPA for potential carcinogenicity. Some structural requirements for potential carcinogenicity within this class of compounds are tentatively deduced.

Anilides↗
PubMed1977

Testing of pesticide toxicity in tissue culture.

The effect of pesticides on cell growth and on the cell layer was examined. The pesticides under study had a similar toxicity for the cell suspension and for the cell layer. Vital staining of the cells allowed a more sensitive determination of the cytotoxic concentrations than did the studies on cell morphology without staining. No correlation was found between the cytotoxic concentrations and LD50 values of mammals. The results were compared with those of earlier experiments on rats in which methods of general toxicology and neurotoxicology were applied. Of the eight compounds tested, in six the tissue culture method proved even more sensitive than did the functional neurotoxicological tests. It is suggested that the in vitro method with cultured cells should be used to complement in vivo functional toxicological procedures.

Animals↗
PubMed1975

Analysis for organophosphorus insecticides and metabolites.

Extraction and cleanup methods used for the analysis of organophosphate pesticides are similar to those used for chlorinated hydrocarbons but differ in some important details. Many organophosphates are lost during extraction of acetonitrile solutions containing organophosphates with petroleum ether; dichloromethane is substituted. Also, cleanup by column chromatography on mixed adsorbents containing charcoal results in better recoveries than can be obtained on Florisil alone. The detectors used for measurement of organophosphates by GLC are almost unique for this group of compounds. TLC is very useful for confirming the identities of the compounds, and several promising optical methods are available for their measurement. Methods for the analysis of metabolites of this group are basically similar, since all organophosphates undergo dealkylation reactions and cleavage of the acid anhydride bond. However, measurement of the polar group which is removed during phosphorylation or other reactions involving cleavage of the acid anhydride bond is a problem unique for each compound.

Charcoal↗
PubMed1979

Effect of toxogonin and P2S on the toxicity of carbamates and organophosphorus compounds.

Toxogonin (80 mg/kg intraperitoneally) given 15 min. prior to the administration of organophosphorus insecticides dimethoate, malathion, parathion and azinphos-methyl, organophosphorus warfare agents soman and tabun, or carbamates physostigmine, pyridostigmine and aldicarb, reduced the toxicity in mice of these agents by increasing their LD50 dose 1.5-3 fold. The toxicity of the carbamate insecticide carbaryl, however, was significantly increased by toxogonin. Similar results were obtained for P2S (150 mg/kg intraperitoneally) with respect to the toxicity of dimethoate, soman and pyridostigmine, whereas no effect could be detected on the toxicity of tabun. Only a slight reduction in the toxicity of physostigmine was observed. The acetylcholinesterase activity in erythrocytes, cerebrum and diaphragm of surviving mice 20 hours after organophosphate intoxication was similar both in toxogonin and P2S treated animals and untreated animals.

Animals↗